1.1. Field of the Invention
The present invention relates to electronic mail. In particular, it relates to a method and system for processing electronic mail, wherein mails are stored in a space efficient way by removing redundancy from the content.
1.2. Description and Disadvantages of Prior Art
A prior art mail system structure is given in FIG. 1 in a rough overview form. A client 10 to a mail server A 12 sends and receives mails to and from, respectively, a mail server B 14 and a client 16 to server B.
US patent application publication No. US 2004/0044735 A1 discloses a prior art e-mail processing method and system, which is intended to remove redundancy in an e-mail thread. It works at the client side exclusively. On client side a new mail is created wherein redundant parts are eliminated by a compare process, which is based on a text compare, and on a header compare procedure. It is cited there from as follows:                “[0038] . . . First, the plurality of e-mail messages are compared with each other, via step 410. Preferably, a comparison program is utilized to compare the plurality of email messages with each other. Next, a portion of at least one of the plurality of email messages is removed that is duplicative of a portion of another of the plurality of email messages, via step 420.        [0039] The comparison program implemented by the method in accordance with present invention can compare the text of the email message, the headers of the email messages, or any of a variety of parameters present within the email message in order to minimize the redundancy between email messages. Accordingly, one of ordinary skill in the art will readily recognize that a variety of implementations could be employed to compare the email messages while remaining within the spirit and scope of the present invention.” (end of prior art citation).        
This prior art method is performed at the client side, as indicated by the circles 18. Generally, a huge amount (N) of different clients are connected to a single mail server. This however, might be regarded in many cases disadvantageous compared to a server-side doing, as the mail servers have usually the additional job to provide a respective backup/archiving server 19 A, 19B with the data to be stored. Thus, it would be more advantageous to remove redundancy already at the server, as this would save enormous amounts of storage space during normal operation and backup, and would reduce the traffic between each client (N often greater than 100,000) and its mail server. This aspect is of increasing importance due to increasing legal obligations imparted on the handling of e-mails regarding documentation and liability purposes in business, and due to the general tendency to do more and more communication in an electronic way.
Disadvantageously, this prior art method does not disclose details on how a compare process is performed in detail, and which mails are to be compared with each other. Further, no precise disclosure is given what has to be done if no doubtless decision is obtainable out of the compare step.
Further, it cannot be implemented at a mail server 12 or 14 for working effectively, where mails from thousands of different mail senders are to be compared with thousands of different mail receivers because a plain text compare combined with preceding header field analysis is not an effective means to decide, which mails belong to the same e-mail thread.
1.3. Objectives of the Invention
It is thus an objective of the present invention to provide a method and system, which is adequate for server operation.